Slide-valve



QNo Modeli) C. M. GIDDINGS.

SLIDE VALVE.

Patented Mar. 17,1885.

WIT/VESSES N. PETER Phmqumognplwr. washnglnn. at;

y UNITED l STATES l `PATENT OFFICE.

CHARLES M. GIDDINGS, OF MASSILLON, OHIO.

SLIDE-VALVE.

SPECIFIQATION forming part of Letters Patent No. 314,120, dated March 17, 1885. Application filed Oclobcr 3, 1884. (No model.)

equilibrium slide-valves for steam-engines,tlie

object being to provide duplex inductionopenings from'the valve to the cylinder-ports,

to the end that steam is admitted more freely,

and consequently the steam-pressure in the.

cylinder approximates more nearly the boilerpressure than with ordinary slide-valves. A further object is to provide a cover integral with the valve proper, and inclosing a chamber for the live steam that is admitted into said chamber from the inner side of the valve, and the valve provided with two small orices, the one leading from the live-steam chamber in the valve to the steam-chest inclosing the valve, to admit steam to the latter and give a pressure on the valve to counterbalance the internal outward pressure, and hold the valve to its seat, and the other orifice leading from the chamber of the steam-chest through the valve and into the exhaust-port, to relieve an excess of pressure required in the steam-chest. A further object is to provide an inclined way for the valve to slide upon, and a friction-surface on the back of the valve and a spring to engage the same, to the end that the valve is held to its seat when steam is shut off. A further object is to provide arib or projecting surface on the bottomV of the valve,and the rib and the wayin which the valve travels marked with such lines as will indicate the position of ports, bridges, or such point-s as will enable the operator to set the valve.

With these objects in view my invention consists in certain features of construction and in combination of parts hereinafter described, and pointed outin the claims.

In the accompanying drawings, Figures l and 2 are longitudinal sections through the valve and'adjaeentportions of the cylinder, showing in Fig. 1 the valve in position to admit steam into the left-hand end of the cylinder and to exhaust the right-hand end, while in Fig. 2 both ports Vare closed by the valve. Fig. 3 is a transverse section of the valve -on the line of x m, Fig. 1. Fig. 4 is a plan view of the face of the valve. Fig. 5 is a view in perspective of the outside of the valve, and showing a portion of the inside surface of the steam-chest, including the way on which the valve travels. Fig. Gis aview in perspective of the valve, with portions of the outer wall broken away, showing the internal construction, and showing also the lines drawn onthe outside corresponding with certain portions on the'inside,and by means of which the valve .is set.A

sidesD and D. The more modern slide-valves for lvarious reasons, among which may be mentioned the faeility'with which the con` densed water is ejected from the cylinder, are

usually arranged along the side of the cylinder, so that the face of the, valve is vertical and the valve rests on the lower side thereof, which in the illustrated valve is the side D, that slides on a suitable way, K, at the bottom of the steam-chest. The side D isinclined or beveled, as shown in Fig..3, and the way K, over which it slides, is ofcourse inclined to correspond, and the tendency of these inclined surfaces is to keep the face ofthe valve against its seat over the parts, so that it is less liable to rattle when the steam is shutoff, and under all circumstances will tend toward the seat. To the same end the spring Z is provided, and

is attached to the steam-chest eoverL in such a lmanneitliat it presses upon the raised portion c,that is dressed off and forms a slide for the spring to act against. The arrangement of parts is such that the pressure of the spring against the valve is merely nominal so long as the valve is in its proper position, but the IOO spring would oppose strong resistance against the valve being forced back from its seat. K is the upper wall, and L the end walls, of the steam-chest. As the part C covers the ports so that these cannot be seen to set the valve by, I have provided a rib, d, that is dressed off and is marked to indicate the central and cut-off points of the valve, while the slide on which the valve rests may have marks to indicate the position of the ports in the cylinder, and by means of these marks the valve may be readily set accurately. The line M on the rib d corresponds with the points B, and the line m indicates Lthe center of the valve. The line M on the bottom of the steam chest or way K corresponds with the points c. The cylinder is provided, as usual, with the ports E, and has the exhaust-ports F and the induction-port G, with corresponding chambers, F and G. The chambers F are connected below with the exhaust-pipe, and the chamber Gis connected on the top with the steam-pipe. It will be seen that the steam from the boiler all enters under the valve through the port G, and that the chamber C and ports c are always full of live steam. It is evident that the pressure of steam against the part C will be considerably in excess of the pressure on the parts B, and the valve under such conditions would be forced away from its seat. To prevent this I have provided the plug H, that is screwed into a threaded orifice in the side D', and located so as to lead into the live-steam chamber C. A small orifice, h, through the plug admits steam from the chamber G to the steam-chest that incloses the valve, by means of which a pressure of steam is had on the outside ofthe valve to hold it to its seat. If the orifice h were of any considerable size, there would soon be had approximately boiler-pressure outside of the valve, which pressure, as aforesaid, being only to hold the valve against its seat, would be greatly in excess of the pressure necessary for this purpose. If the orifice h were materially decreased in size, it would only retard-the accumulation of steam,and consequent pressure in the steam-chest, but eventually, in the absence of leakage and condensation, a full pressure would be had. To prevent this I have provided a second plug, I, similar to the plug II, except that the relief-opening z' through it may be of different size than the orifice h. The plug -I is screwed into a hole in the side D', that is located so that the end of the plug` enters one of the chambers a, that are always in open relation with the contiguous exhaustport F. rlhe result is that the opening i, aecording to its relative size to the opening h, more or less relieves the pressure in the steamchest and equalizes the pressure on the valve. It is not claimed that a valve can be accurately balanced in this manner; but as with afull pressure of steam in the chest the valve only labors under the ordinary conditions of slidevalves it is evident that any decrease in this pressure down to the minimum pressure that will hold thevvalve to its seat will Ybe ank improvement on the ordinary slide-valves. Of course the steam that blows through the oriee i is lost, but, owing to the minuteness of this orifice, the amount is so small that it is of no consequence. rlhe orifices 7i and t' might be made directly in the side D; but as the metal of the valve is usually soft cast-iron the action of the steam would soon enlarge the oriiices. It is therefore advisable to use the plugs H and I, the initial cost of which is but trifling, and these plugs may be made of hard metal, to resist the action of the steam, and may be takenout and cleaned or renewed at any time without disturbing the valve. It' the cover or part G were removed and the ports Z were closed or omitted, we would have substantially a common D-slide valve, with the steam entering the steam-chest through the port G instead 'of entering direct from a steam-pipe inthe usual manner. In such a case the valve would terminate at either end respectively with the louter ends of the parts B at the points B.

The oiiice of the part C is to confine the steam in the chamber C, for the purpose of vequalizing the pressure in a manner and for the purpose already shown, and whether it is or is not made a part of the valve will have nothing to do with admitting steam to or cutting it off or exhausting it from the ports of the cylinder. rIhe valve proper, terminating, as aforesaid, at the points B', is supposed tohavetheusuallap, lead, &c.,and-when in a central position closes both ports E, as shown inFig. 2. It the valveis moved in one direction, for instance, toward the right hand, as shown in Fig. l, when the end of thervalve at B is drawn back from the point e, so as to uncover aportion of the port E, steam is of ICO course admitted to this end of the cylinder in the usual manner. At the same time the opposite end of this diaphragm B has moved beyond the point g, so that steam is admitted into the duct or port Z), and passes over into the port E. The arrangement of parts is such that the distance from the point B to the inner edge of the opposite end of thc same diaphragm B is the same as from the point c to the nearest point g, and when,therefore,a given opening is had at the end of the valve at B, the same sized opening is had at the point g, leading into the duct b. By means of these auxiliary ports or passage-ways b, when the valve commences to open, double the area of port-opening or passage-way for steam is had as is had with ordinary slide-valves, and, as is well known, is a desirable feature, especially in quick-running engines, and considerably increases the power of such engines; also, equalizing the pressure on the valve, so that it is moved with little power, renders this construction especially adapted to reversible engines. Y

The common slide-valve engine,- on vaccount of its eheapness and simplicity, has been, and probably will continue to be, largely used for ordinary purposes7 and any improvement on this class of engines that can be eftectivcwith- IIO out materially increasing the initial cost will of course be very desirable.

The improvement herein described would add so little to the initial cost of engines that probably engine-builders would :not consider it worthwhile to change their price-list on account of the same.

l. An equalizing slide-valve consisting, essentially, of the parts A, B, and C, arranged with intervening spaces, as described, in combination with a valve-seat provided with the five ports E, F, and G, substantially as set forth.

2. rIhe combination, with a cylinder having an induction-port, exhaust-ports located on opposite sides of the induction-port, and the ports E,outside of the exhaustports, of theV valve having the induction-ports c and I), and the exhaust cups or chambers a, substantially as set forth;

3. An equalizing slide-valve provided with the cover C and the chambers a and C, and the openings It and z', all arranged substantially as set forth.

4. In an equalizing slide-valve, the combination, with the cover C and the chambers a and C', the plug H, provided with` the orifice h in open relation with the live-steam chamber C', and the chamber of the steam-chest, of the plug I, provided with the relief-orifice i in open relation with the chamber of the steam-chest and with the exhaust, substantially as set forth.

by the face of the valve is held in close contact with its seat, substantially as set forth.

G. In an equalizing slide-valve, the eomb1- nation, with a spring attached to the steamchest cover, of a raised surface on the back of the valve adapted to form a track for the sprin g to travel upon, and the parts so arrangedthat by the engagement of the spring with the ralsed track the valve is held to its seat when the pressure of steam is removed, substantially as set forth. p u

7. In an equalizing slide-valve, the combination, with a valve-easing having points or marks M, of a valve located within said c as ing, and provided with a projecting rib havlng the points or marks M thereon, the said points being arranged with relation to the ports as described, whereby the valve can be easily and quickly set, substantially as set forth.

In testimony whereof I sign this specification, in the presence of two witnesses, this 13th day of September, 1884.

CHARLES M. GIDDINGS.

Vitnesses:

' GEO. HANsoN,

J. W. STRINGER. 

